摘要
为探究硫胺素酶Ⅰ在黏细菌中的生理功能,选取Corallococcus sp.EGB、Myxococcus xanthus DK1622和Cystobacter sp.1404三种不同种属的黏细菌,研究3种黏细菌基因组中硫胺素合成与菌株生长发育的关系。结果显示,3种黏细菌基因组中均具有完整的硫胺素合成途径,且具有硫胺素合成前体嘧啶(4-amino-5-hydroxymethyl-2-methylpyrimidine,HMP)回收相关基因,但未发现硫胺素或其前体噻唑回收相关基因;HMP合成酶基因thiC上游存在的焦磷酸硫胺素核糖开关(TPP-riboswitch)可根据环境中硫胺素浓度调控thiC基因的转录水平。菌株DK1622及其硫胺素酶Ⅰ敲除突变株CL1003中分别插入thiC基因,构建突变菌株CL1006和CL1007,发现CL1006在无硫胺素培养基中需要额外添加硫胺素或HMP才能恢复生长,但相比于硫胺素处理组,HMP处理组菌落直径显著增加了9.0%;CL1007只能在添加HMP平板中生长,单独添加完整的硫胺素并不能使其恢复生长,但当硫胺素酶CcThi1和硫胺素共同添加时,CL1007的生长得到恢复。结果表明,黏细菌不直接利用外源硫胺素,但可通过硫胺素酶Ⅰ将其分解成嘧啶前体被利用。
Three genera of myxobacteria including Corallococcus sp.EGB,Myxococcus xanthus DK1622 and Cystobacter sp.1404 were used to study the physiological function of thiamine I from myxobacteria.The relationship between the pathway of synthesizing thiamine and the growth and development of strain in the genomes of three myxobacteria was identified.The results showed that three myxobacteria had complete pathway of synthesizing thiamine in their genomes,and contained genes related to the recovery of thiamine precursor pyrimidine(4-amino-5-hydroxymethyl-2-methylpyrimidine,HMP),but no genes related to the recovery of thiamine or its precursor thiazole was found.The presence of TPP-riboswitch at the upstream of the HMP synthase gene thiC regulated the transcription level of the thiC gene based on the concentration of thiamine in the environment.Mutant CL1006 and Mutant CL1007 were constructed by inserting the thiC gene into strain DK1622 and thiaminase I knockout mutant CL1003,respectively.It was found that CL1006 required additional addition of thiamine or HMP to recover growth in thiamine-free medium.The HMP treatment group significantly increased the colony diameter by 9.0%compared to the thiamine-treated group.CL1007 only grew on HMP plates,and the addition of intact thiamine alone did not restore its growth.However,when CcThi1 and thiamine were added together,the growth of CL1007 was restored.It is indicated that myxobacteria do not directly utilize exogenous thiamine,but can utilize pyrimidine precursors produced by decomposing thiamine through thiaminase I.
作者
齐梦祎
夏丞垚
纪燕玲
黄彦
李周坤
叶现丰
崔中利
QI Mengyi;XIA Chengyao;JI Yanling;HUANG Yan;LI Zhoukun;YE Xianfeng;CUI Zhongli(College of Life Science/Key Laboratory of Agricultural Environmental Microbiology,Ministry of Agriculture and Rural Affairs,Nanjing Agricultural University,Nanjing 210095,China;School of Pharmaceutical Sciences,Xiamen University,Xiamen 361102,China)
出处
《华中农业大学学报》
CAS
CSCD
北大核心
2024年第4期204-211,共8页
Journal of Huazhong Agricultural University
基金
国家自然科学基金项目(32170123,32371730,32370119)。
